CN1345363A - Bar composition containing solid amphoteric surfactants - Google Patents

Abstract

The present invention relates to personal wash bar compositions, particularly compositions comprising (1) lathering anionic surfactants (e.g., sodium acyl isethionate or fatty acid soap); (2) specific solid, less hygroscopic amphoteric surfactants (e.g., disodium N-lauryl iminodipropionate). The invention relates to the incorporation of significant levels of said solid amphoteric surfactant into the specific bar compositions to achieve superior skin mildness and bar user properties. The invention especially addresses the advantages of using solid, less hygroscopic amphoteric surfactants to reduce the processing difficulties in extrusion and modified extrusion processes.

Description

Block composition containing solid amphoteric surfactant

The present invention relates to personal cleansing bar compositions, particularly those manufactured by extrusion processing, comprising: (1) a lathering anionic surfactant (such as sodium acyl isethionate) and (2) a Physical parameters of solid amphoteric surfactants (such as disodium N-lauryl iminodipropionate). The present invention also relates to the incorporation of higher levels of said amphoteric surfactants into specific cake compositions.

By carefully balancing the weight ratios of surfactants, structurants/fillers, and emollients, the blocks can be successfully processed by extrusion with high end quality (eg, satisfactory block hardness and foam). In particular, the present invention relates to the incorporation of such amphoteric surfactants into personal wash bars to reduce processing difficulties (eg, reduced mixing and drying times, reduced stickiness during extrusion). The solid amphoteric surfactant in the block also contributes to superior skin mildness when compared to the inclusion of other types of amphoteric surfactants.

Finally, the present invention proposes a special method of handling said solid amphoteric surfactants during bulk processing.

Anionic surfactants are used as primary active agents in many skin cleansers. Despite their many advantages, such as good foaming properties, they tend to irritate the skin. For example, the use of fatty acid soaps often causes irritation and cracking of the skin, especially in colder climates. One way to generally reduce the harshness produced by anionic surfactants, including fatty acid soaps, is to use other surfactants, such as amphoteric surfactants, as co-activators to partially replace the anionic surfactants in skin cleansing products.

While not wishing to be bound by theory, it is believed that amphoteric surfactants reduce skin irritation by forming colloidal aggregates (micelles, capsules, and liquid crystals) with skin-irritating anionic surfactants in aqueous personal wash solutions, preventing anionic surfactants from Penetration and binding of skin proteins by agents.

However, the use of amphoteric surfactants in solid skin cleansing bars can introduce problems in bar processing and performance. For example, incorporation of 10% to 15% by weight of cocamidopropyl betaine (a commonly used amphoteric surfactant) into extruded synthetic surfactant blocks gives sticky formulations, thus severely slowing down extrusion productivity . Including the same amount of cocamidopropyl betaine in the fatty acid soap block will increase the time period in mixing and drying. Most amphoteric surfactants are gelish and sensitive to handling (eg thinning/gelling response to shear). These properties slow down or even stop the extrusion/plotting, resulting in stickiness to the stamping die, which will impart undesired gelatinization and softness to the block.

Additionally, many of these amphoteric surfactants are difficult to dry into low moisture solids such as powders or tablets. They are therefore commercially available as dilute aqueous solutions, bringing an extra amount of water to the mixer, prolonging the mixing-drying time.

Therefore, there is a need in the art for amphoteric surfactants that are non-tacky, solid with low moisture, can be used to reduce mixing/drying cycles, and can be processed continuously with high productivity by said extrusion/plotting technology. The high level of amphoteric surfactant should be capable of incorporation into extruded blocks (including synthetic surfactants or fatty acid soaps or mixtures thereof) without causing processing difficulties and negatively affecting block user properties such as foaming and block hardness . It is preferred that bar performance (eg lathering) be enhanced by the inclusion of the amphoteric surfactant.

It is also desirable to identify amphoteric surfactants that may be more effective than other amphoteric surfactants in reducing skin irritation caused by anionic surfactants or fatty acid soaps in bars.

When compared to fatty acid soap bars, it must be noted that bars containing synthetic surfactants have a different formulation space (fbrmulation space). While bars containing synthetic surfactants require additional structurants such as fatty acids and waxes, fatty acid soap bars do not. The processing procedures used to synthesize surfactant bars and fatty acid soap bars are also quite different, as described in the many patents covering this field.

Therefore, it is technically very challenging to identify an amphoteric surfactant that meets both the synthetic bar and fatty acid bar requirements listed above. However, applicants have unexpectedly found that amphoteric surfactants defined by certain physical parameters fulfill these needs.

The use of solid amphoteric surfactants such as disodium N-lauryliminodipropionate in block and liquid compositions is not new per se. For example, such amphoteric surfactants have been incorporated into acidic, low pH blocks containing synthetic anionic surfactants. Disodium N-lauryliminodipropionate was used in elastic rubber mass prepared by melt casting. The amphoteric surfactant is also commonly used as a mild detergent in liquid cleansers such as shampoos and shower body washes.

US Patent No. 3,442,812 to J. Bamhurst et al. (assigned to Colgate-Palmolive Co.) discusses soap-free syndet bars with acidic lather with skin conditioning benefits. The block foam must be acidic, with a pH of less than 6 (ie, a pH of 5 or below, as described in column 2, lines 42-68 and claims 1, 12, 13 of said patent). Disodium N-lauryl iminodipropionate is cited as one amphoteric surfactant used. This patent fails to recognize the importance of using solid amphoteric surfactants in the block to improve processability.

Furthermore, the patent fails to recognize that disodium N-lauryliminodipropionate (or other compounds having the properties described in the subject invention) is less effective in reducing skin irritation caused by anionic surfactants when compared to other amphoteric surfactants. The advantages of amphoteric surfactants with defined physical parameters). In this application, the low pH requirement also prevents the use of fatty acid soaps (pH>7) as components of the block.

Conversely, the amphoteric surfactants defined by the subject invention, such as disodium N-lauryl iminodipropionate, can be used as solid co-activators in fatty acid soaps and synthetic surfactant based extruded bars. The blocks of the invention must have a neutral or alkaline pH (ie 6 to 12, preferably 6 to 10, most preferably 6.5 to 9). The title application states that the use of these solid amphoteric surfactants: (1) achieves improved processing; (2) achieves superior skin mildness when compared to other amphoteric surfactants. These features are neither suggested nor suggested in the mentioned patents.

U.S. Patent No. 4,080,310 to L. Ng et al. (assigned to Beecham Group Ltd.) refers to an amphoteric conditioning shampoo containing 5 to 50% by weight of an amphoteric detergent as a single detergent and 0.5 to 3.0% weight of cationic or quaternary ammonium resins. The pH is from 3 to 9, preferably from 4 to 7. For example, the amphoteric detergent may be eg N-alkyl-β-alanine or N-alkyl-β-iminodipropionate. Suitable resins are cationic polyamide polymers or cationic starch or cellulose derivatives.

This patent does not teach the use of a solid amphoteric surfactant as defined (eg, disodium N-lauryliminodipropionate) in skin cleansing bars to facilitate processing while reducing anionic irritation. In contrast, in the title application, disodium N-lauryliminodipropionate is added to synthetic surfactants and/or fatty acid soap based extruded blocks to (1) facilitate processing of the blocks; (2) Enhance the mildness of the bar formulation; (3) enhance the creaminess of the bar foam.

US Patent No. 4,207,198 to D. Kenkare (assigned to the Colgate-Palmolive Company) discusses resilient bars with improved shape retention and improved foaming ability when stored at elevated temperatures. The bars contain organic detergents (ammonium or lower alkanolammonium salts of anionic organic detergents), or mixtures of these anionic detergents with amphoteric organic detergents, gelatin and lower di- or polyhydric alcohols. The claimed amphoteric detergents include N-alkyl-beta-iminodipropionates. The blocks are produced by melt casting methods and exhibit a large degree of elasticity. In claim 1, the rubbery block is described as "it can be pressed from a thickness of 2 cm to a thickness of 1 cm with the thumb and forefinger, and after the pressure is released, it returns to a thickness of 2 cm (not exceeding the range of 1 mm) within 5 seconds".

In contrast, the amphoteric surfactants of the subject invention, such as disodium N-lauryliminodipropionate, are used in blocks prepared by an extrusion process that requires rigid and solid properties of the extrudate. The most important thing is to add the solid amphoteric surfactant in the extruded block, which helps to reduce the softness and elasticity of the block. Accordingly, the discussion of the mentioned patents departs from the field of the title application.

U.S. Patent No. 4,328,131 to J. Carson et al. (assigned to the Colgate-Palmolive Company) proposes a resilient, rubbery detergent bar with improved high temperature stability (described in claim 1 as "it can be held with the thumb and forefinger The 2cm thickness is pressed into 1cm thickness, and after the pressure is released, it returns to 2cm thickness within 5 seconds (not exceeding the range of 1mm)"). This is why it retains its shape better when stored at slightly higher than normal storage temperatures, it consists of amphoteric and anionic synthetic organic detergents distributed throughout the block in the form of very small air bubbles, gelatin, water and A mixture of insoluble gases.

Amphoteric surfactants used include disodium N-alkyl-β-iminodipropionates. Blocks were prepared by the melt casting method. In contrast, the subject application uses disodium N-lauryliminodipropionate in blocks prepared by an extrusion process that requires rigid and solid properties of the extrudate. Most importantly, the solid amphoteric surfactant is added to the extruded block in order to reduce the softness and elasticity of the block. Thus, the discussion of the mentioned patents deviates from the field of the title application.

U.S. Patent No. 3,962,418 filed by R Birkofer proposes a mild, thickened liquid shampoo composition with conditioning properties comprising 4-8% of anionic surfactants, zwitterionic and amphoteric surfactants, polyethylene glycol Oxylated nonionic surfactants and cationic cellulose ether thickeners and conditioners. Amphoteric surfactants used include disodium N-alkyl-β-iminodipropionates. However, this patent does not teach that the use of solid disodium N-lauryliminodipropionate in solid skin cleansing bars facilitates bar processing while reducing skin irritation.

In contrast, in the title application, disodium N-lauryliminodipropionate is added to synthetic surfactants and/or fatty acid soap based extruded bars to simultaneously facilitate bar processing and enhance the mildness of the bar formulation. properties and enhance the creaminess of the bar foam.

In short, the above patents, individually or in combination, fail to address or suggest the identification and incorporation of specific types of solid amphoteric surfactants in personal wash bars when compared to the incorporation of other types of amphoteric surfactants, The personal washing block added with a special type of solid amphoteric surfactant has the following properties at the same time:

(1) significantly improving the mixing-drying and extrusion process;

(2) significantly improve the mildness of the block when compared to the addition of other types of amphoteric surfactants to the block; and

(3) Improved blistering of the block without negatively affecting the firmness of the block.

Applicants have surprisingly and unexpectedly discovered that all of these goals can be achieved simultaneously by including a specific type of solid amphoteric surfactant in the extruded mass. That is to carefully select solid amphoteric surfactants (that is, have a special melting temperature or glass transition temperature range in the solid state, which is rare in the class of amphoteric surfactants) and to use higher levels of amphoteric surfactants. Incorporated into personal wash bars, the following four goals can be achieved at the same time:

(1) As described in the process section, the high amphoteric surfactant-containing blocks can be processed using current extrusion-stamping techniques;

(2) Significantly reduce the mixing/drying cycle;

(3) Significantly reduced skin irritation when compared to formulations containing other types of amphoteric surfactants; and

(4) Does not negatively affect block hardness and improves blistering.

The applicants have now found that the incorporation of higher levels of non-sticky, solid amphoteric surfactants such as disodium N-lauryliminodipropionate into personal wash bar compositions simultaneously provides the following benefits :

(1) The blocks containing high levels of amphoteric surfactants can be processed using current extrusion-stamping techniques, unlike the processing difficulties encountered when including comparable levels of other types of amphoteric surfactants in the blocks form a contrast;

(2) Significantly reduce the mixing/drying cycle;

(3) Significantly reduced skin irritation when compared to formulations containing other types of amphoteric surfactants; and

(4) The hardness of the block is not adversely affected, and blistering is improved.

More specifically, the subject invention includes:

(A): a skin cleansing block composition, containing (weight percent)

(1) About 15-97% foaming anionic surfactant;

(2) 0-70% organic and inorganic structuring agents and fillers;

(3) 0-30% emollients and humectants;

(4) 0-5% hygroscopic amphoteric surfactants other than those defined in (5); and

(5) 3-25% of special amphoteric surfactants in solid form when the temperature range is between 18°C and 60°C;

The amphoteric surfactant is defined as a crystalline solid having a melting temperature (T m ) above 18°C, preferably above 20°C, most preferably above 25°C; alternatively defined as a crystalline solid having a melting temperature (T _m ) above 18°C, preferably above an amorphous solid with a glass transition temperature (T _g ) above 20°C, most preferably above 25°C;

The amphoteric surfactant should contain less than 5% water, preferably less than 2% water, most preferably less than 0.5% water.

A preferred amphoteric surfactant is disodium N-lauryl iminodipropionate.

The block composition (A) should provide a hard, non-resilient block, in contrast to the elastic blocks taught by US Pat. No. 4,207,198 and US Pat. No. 4,328,131.

A preferred method of processing the cake composition is by extrusion as described in the subject patent application, and preferably by coextrusion of the high content of amphoteric surfactant (A ): (5) added to the block.

The present invention will be further described according to accompanying drawing now, and this description is exemplary only; Wherein

- Figure 1. shows the comparison of the hardness of blocks containing a solid amphoteric surfactant (Deriphat 160) as defined by the invention with the hardness of blocks containing a liquid, hygroscopic amphoteric surfactant (CAP betaine). Harder blocks are less permeable;

- Figure 2. Shows the foam volume of a block containing a solid amphoteric surfactant (Deriphat 160) compared to a block containing a liquid, hygroscopic amphoteric surfactant (CAP Betaine); also shows DEFI plus Foam volume of Deriphat 160 compared to that of DEFI alone;

- Figure 3. Shows the foam volume of DEFI/Deriphat 160 at different weight ratios.

- Figure 4. Shows the results of a 4-day skin contact test on human skin: DEFI/Deriphat 160 blend compared to different types of DEFI/liquid, hygroscopic amphoteric surfactant blends and DEFI alone; and

- Figure 5. Shows the results of a 4-day skin contact test on human skin: DEFI/Deriphat 160 mixture compared to DEFI/CAP betaine mixtures in different weight ratios.

Excellent skin mildness has become one of the most important consumer attributes driving product innovation in the field of skin cleansing bars. One of the approaches used to enhance the mildness and lathering of bars is to add amphoteric co-surfactants to the bars to reduce skin irritation. However, most of said amphoteric surfactants (eg cocamidopropyl betaine) available on the market are in the form of viscous liquids or gels, even at high active (low water) content.

Adding high levels of these amphoteric surfactants to the block causes processing difficulties (such as prolonging the mixing/drying time period, slowing extrusion and causing sticking to the stamping die) and causing the block to be softer and gelatinized. Therefore, it is desirable to have a low moisture, solid form of the amphoteric surfactant for incorporation into bars as a major ingredient. It is even more desirable that these solid amphoteric surfactants can reduce skin irritation caused by anionic surfactants in the block more effectively than other types of amphoteric surfactants.

The present invention relates to novel personal cleansing bars prepared by using the extrusion process described in the process section of the titled invention.

Unexpectedly, by incorporating a specific type of solid amphoteric surfactant (that is, defined by a specific range of melting temperature and glass transition temperature) into a skin cleansing bar, the following goals can be simultaneously met:

(1) The blocks containing high levels of amphoteric surfactants can be processed using current extrusion-stamping techniques, which is compounded by the processing difficulties encountered in including comparable levels of other types of amphoteric surfactants in the blocks control;

(2) Significantly reduce the mixing/drying cycle;

(3) Significantly reduced skin irritation when compared to formulations containing other types of amphoteric surfactants; and

(4) Block hardness is not negatively affected, and foaming is improved.

In particular, the inventors of the subject application have identified a particular class of amphoteric surfactants (such as disodium N-lauryliminodipropionate) that simultaneously meet these needs. Formulation work has shown that these materials can be processed into extruded blocks at higher levels of incorporation without negative impact when compared to liquid or gel-like amphoteric surfactants such as cocamidopropyl betaine. Affects the block hardness.

This class of amphoteric surfactants causes less shear thinning and softening during extrusion/plotting, less stickiness to the stamping die when compared to other classes of amphoteric surfactants. For example, since disodium N-lauryl iminodipropionate is in the form of a low moisture, dry powder, no additional amount of water is brought to the mix. Thus, the mixing-drying time period, which is particularly critical for the fatty acid soap-based bars, is greatly reduced. Clinical studies have shown that disodium N-lauryliminodipropionate is more effective than other amphoteric surfactants in reducing skin irritation caused by the anionic surfactants in the block.

Percentages (%) used in the subject invention are by weight.

More specifically, the subject invention includes:

(A): Skin cleansing bar composition, comprising

(1) 15 to 97%, preferably 25 to 97%, of a lathering anionic surfactant; and

(2) 3 to 25%, preferably 4 to 20%, most preferably 5 to 15% of a special amphoteric surfactant in solid form at a temperature range between 18°C and 60°C.

The weight ratio of anionic surfactant to amphoteric surfactant should be equal to and greater than 1:1.5, preferably equal to and greater than 1:1, most preferably equal to and greater than 2:1. Below this weight ratio, block foam tends to be a large foam and is unstable.

The amphoteric surfactant is defined as a crystalline solid having a melting temperature (T _m ) above 18°C, preferably above 20°C, most preferably above 25°C; in another case, the amphoteric surfactant is defined as having a temperature of 18 An amorphous solid having a glass transition temperature ( _Tg ) above 20°C, preferably above 20°C, most preferably above 25°C.

The solid amphoteric surfactant should contain less than 5% water, preferably less than 2% water, most preferably less than 0.5% water.

The solid amphoteric surfactant should absorb 35% or less of its own weight in water at a relative humidity of 80% and a temperature of 26°C.

Preferably the amphoteric surfactant is disodium N-lauryl iminodipropionate.

The block composition also contains:

(1) 0-70% by weight of organic and inorganic structuring agents and fillers;

(2) 0-30% by weight of emollients and humectants;

(3) 0-5% by weight of conventional, hygroscopic amphoteric surfactants; and

(4) 0-20% by weight of nonionic surfactant.

In direct contrast to the definition of melt-cast elastomeric blocks set forth by US Patent No. 4,207,198 and US Patent No. 4,328,131, the block composition (A) provides a hard, non-elastic extruded block. In particular, the 2 cm thickness of composition (A) cannot be pressed with the thumb and forefinger to a 1 cm thickness without permanently compressing the block, and upon release of the pressure it will recover within 5 seconds Less than 2cm thickness (not exceeding 1mm range).

A preferred processing method for the block composition is by the extrusion method described in detail in the process section of the titled patent application. As described in detail in the process section, the high level of amphoteric surfactant is preferably incorporated into the block by coextrusion.

Accordingly, the block composition (A) will be described in detail.

For example, the anionic surfactant can be an aliphatic sulfonate, such as a primary paraffin (such as C ₈ -C ₂₂ ) sulfonate, a primary paraffin (such as C ₈ -C ₂₂ ) disulfonate, C ₈ -C ₂₂ alkene sulfonate, C ₈ -C ₂₂ hydroxyalkane sulfonate or alkyl glyceryl ether sulfonate (AGS); or aromatic sulfonate such as alkylbenzene sulfonate.

The anion may also be an alkyl sulfate (such as a C ₁₂ -C ₁₈ alkyl sulfate) or an alkyl ether sulfate (including an alkyl glyceryl ether sulfate). The alkyl ether sulfates are those compounds having the formula:

RO( _CH2CH2O ) _nSO3M wherein R is an alkyl or alkenyl group having 8 to 18 carbons, preferably 12 to 18 carbons, and n is _{an average} value greater than 1.0, preferably 2 to 3; M is a solubilizing cation such as sodium, potassium, ammonium or substituted ammonium. Ammonium and sodium lauryl ether sulfate are preferred.

The anions may also be alkyl sulfosuccinates (including mono and dialkyl esters such as _C6 - _C22 sulfosuccinates); alkyl and acyl taurates, alkyl and acyl Sarcosinates, sulfoacetates, C ₈ -C ₂₂ alkyl phosphates and phosphates, alkyl phosphates and alkoxyalkyl phosphates, acyl lactylates, succinic acid and maleic acid C ₈ -C ₂₂ monoalkyl ester salts of acids, sulfoacetates and acyl isethionates.

The sulfosuccinate salt may be a monoalkyl sulfosuccinate salt of the formula:

R ⁴ O ₂ CCH ₂ CH(SO ₃ M)CO ₂ M The amido-MEA sulfosuccinate salt of the formula:

R ⁴ CONHCH ₂ CH ₂ O ₂ CCH ₂ CH(SO ₃ M)CO ₂ M wherein R ⁴ is a C ₈ to C ₂₂ alkyl group and M is a solubilizing cation; amido-MIPA sulfosuccinic acid of the formula Ester salt

RCONH( _CH2 )CH( _CH3 )( _SO3M ) _CO2M wherein M is as defined above.

Also included are alkoxylated citrate sulfosuccinates and alkoxylated sulfosuccinates of the formula:

RO—(CH ₂ CH ₂ O) _n COCH ₂ CH(SO ₃ M)CO ₂ M wherein n=1 to 20; M is as defined above.

Sarcosinate is usually determined by the following formula:

RCON(CH ₃ )CH ₂ CO ₂ M wherein R is a C ₈ to C ₂₀ alkyl group and M is a solubilizing cation.

Taurate is usually identified by the following formula:

R ² CONR ³ CH ₂ CH ₂ SO ₃ M wherein R ² is C ₈ to C ₂₀ alkyl, R ³ is C ₁ to C ₄ alkyl, and M is a solubilizing cation.

Another class of anionic surfactants is the carboxylate salts of the formula:

R—(CH ₂ CH ₂ O) _n CO ₂ M wherein, R is a C ₈ to C ₂₀ alkyl group, n is 0 to 20, and M is as defined above.

Another carboxylate that can be used is an amidoalkylpolypeptide carboxylate such as, for example, Seppic's Monteine LCQ ^(R) .

Another surfactant that can be used is a C ₈ -C ₂₄ fatty acid soap (alkyl carboxylate) having the following structure:

R—CO ₂ M ⁺ wherein, R is a C ₈ -C ₂₄ alkyl group, and M ⁺ is a monovalent cation, such as sodium, potassium or ammonium.

Another surfactant that can be used is the C ₈ -C ₁₈ acyl isethionates. These esters are prepared by reacting an alkali metal isethionate with a mixed aliphatic fatty acid having 6 to 18 carbon atoms and an iodine value of less than 20. At least 75% of the mixed fatty acids have 12 to 18 carbon atoms, and up to 25% of the mixed fatty acids have 6 to 10 carbon atoms.

Acyl isethionates, when present, generally range from about 0.5 to 15% by weight of the total composition. Preferably this component is present in an amount from about 1 to about 10%.

其中，R是具有8至18个碳原子的烷基，m是1至4的整数，X和Y是氢或具有1至4个碳原子的烷基，M⁺是一价阳离子，例如钠、钾或铵。The acyl isethionate may be an alkoxylated isethionate as described in US Patent No. 5,393,466 to Ilardi et al., hereby incorporated by reference into the title application. This compound has the general formula:

Wherein, R is an alkyl group having 8 to 18 carbon atoms, m is an integer of 1 to 4, X and Y are hydrogen or an alkyl group having 1 to 4 carbon atoms, and M ⁺ is a monovalent cation such as sodium, potassium or ammonium.

Typically the anionic component will constitute from about 15 to 97% by weight of the composition, preferably from 20 to 90%, most preferably from 25 to 85%.

To the block is added 3 to 25%, preferably 4 to 20%, most preferably 5 to 15% of a particular solid amphoteric surfactant which is in solid form when the temperature ranges between 18°C and 60°C.

The amphoteric surfactant is defined as a crystalline solid having a melting temperature ( _Tm ) above 18°C, preferably above 20°C, most preferably above 25°C; alternatively, the amphoteric surfactant is defined as having An amorphous solid with a glass transition temperature ( _Tg ) below 25°C, preferably below 20°C, most preferably below 18°C.

The solid amphoteric surfactant should contain less than 5% water, preferably less than 2% water, most preferably less than 0.5% water.

The solid amphoteric surfactant should absorb 35% or less of its own weight of water, preferably 30% or less of water at a constant relative humidity of 80% and a temperature of 26°C.

Preferably the solid amphoteric surfactant is disodium N-alkyliminodipropionate having the following molecular structure:

RN—(CH ₂ CH ₂ COONa) ₂ wherein, preferably R is an alkyl functional group, preferably a C ₁₀ -C ₂₂ , most preferably a C ₁₂ -C ₁₈ alkyl functional group.

A preferred example is disodium N-lauryl iminodipropionate, available from Henkel Corp. as

Available under the trade name Deriphat 160.

As shown in Table 1, the hygroscopicity of disodium lauryl iminodipropionate was determined by the three-day water absorption (calculated as a percentage of the weight of the surfactant itself), compared with those of other conventional liquid or hygroscopic amphoteric surfactants. agents for comparison. Table 1 Hygroscopic properties of solid amphoteric surfactants compared with those of other conventional liquid, hygroscopic amphoteric surfactants Types of amphoteric surfactants Total moisture content obtained (%) example: Disodium N-lauryl iminodipropionate 26.0 ¹ Contrast: Coco Betaine 70.0 ¹ Cocamidopropyl Betaine 48.2 ¹ palmityl amidopropyl betaine 46.5 ¹ Isostearylaminopropyl Betaine 44.3 ¹ Cocamidopropyl Hydroxysultaine 59.5 ^{1 1} Data extracted from U.S. Patent No. 5,425,892 (column 11, lines 1-25)

Table 1 shows that the comparative liquid or hygroscopic amphoteric surfactants tend to absorb more water than the specific solid amphoteric surfactants used in the subject invention. Thus, incorporation of the solid amphoteric surfactant in the block provides the following processing advantages:

1) Reduced mixing-drying time period due to bringing less water and less hygroscopicity to the formulation formulation; and

2) The formulation is less sticky during the extrusion, chill roll/grinding and stamping stages, making the high solid amphoteric surfactant mass processable.

As shown in the examples, incorporation of the solid amphoteric surfactant into an anionic surfactant based bar formulation resulted in enhanced creaminess and skin feel of the bar foam upon use.

As shown in the examples, the weight ratio of anionic surfactant to said amphoteric surfactant should be equal to or greater than 1:1.5, preferably 1:1, most preferably 2:1. Below this weight ratio, the foam tends to be a larger foam and is unstable.

In contrast to the definition of melt-cast elastomeric blocks proposed by U.S. Patent No. 4,207,198 and U.S. Patent No. 4,328,131, the block composition (A) provides a firm , Inelastic extruded blocks. Specifically, the composition (A) with a thickness of 2 cm cannot be pressed to a thickness of 1 cm with the thumb and forefinger, and it will return to a thickness of less than 2 cm (within the range of 1 mm) within 5 seconds after the pressure is released.

If the block composition contains synthetic anionic surfactant as the main anionic surfactant (ie equal to and higher than 50%), the block (A) needs to have at least 15%, preferably at least 30% , most preferably at least 45% of optional structurants and fillers. Conversely, if the bar composition contains fatty acid soap as the primary anionic surfactant (ie, at and above 50%), structurants and fillers are optional components.

The structurant system of the present invention is conveniently a mixture of water soluble alkylene oxide compounds and other structurants (i.e. fatty acids, maltodextrins and paraffins), wherein the alkylene oxide compounds make up at least 20% of the structurant system , preferably at least 40%, further wherein said alkylene oxide compound constitutes no more than about 70% by weight of the total composition.

Alkylene oxide compounds include moderately high molecular weight polyalkylene oxides having a suitable melting point (eg, 25°C to 100°C, preferably 45°C to 65°C), in particular polyethylene glycol or mixtures thereof.

The polyethylene glycol (PEG) used may have a molecular weight of 2,000 to 25,000, preferably 3,000 to 10,000. However, in some embodiments of this invention it is preferred to include relatively small amounts of polyethylene glycol having a molecular weight in the range of 50,000 to 500,000, especially about 100,000. Such polyethylene glycols have been found to increase the abrasion resistance of the block. This is believed to be due to the long polymer chains of the block compositions remaining entangled during use, even when they are wet.

If such high molecular weight polyethylene glycol (or any other water-soluble high molecular weight polyalkylene oxide) is used, its amount is preferably 1% to 5% by weight of the composition, more preferably 1% or 1.5% to 4% or 4.5%. These materials will generally be used in combination with a substantial amount of other water soluble structurants such as the above mentioned polyethylene glycols having a molecular weight of 2,000 to 25,000, preferably 3,000 to 10,000.

Water-soluble starches such as maltodextrin may also be included in amounts of 1% to 15% by weight of the total composition.

The water insoluble structurant also has a melting point of 25°C to 100°C, more preferably at least 45°C, especially 50°C to 90°C. Of particular interest to suitable materials are fatty acids, especially those having a carbon chain of 12 to 24 carbon atoms. Examples are lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and mixtures thereof. The sources of these fatty acids are coconut, topped coconut, palm, palm kernel, carnauba and tallow fatty acids and partially or fully hardened or distilled fatty acids. Other suitable water insoluble structurants include alkanols of 8 to 20 carbon atoms, especially cetyl alcohol. These materials typically have a water solubility of less than 5 g/l at 20°C.

The relative proportions of the water-soluble and water-insoluble structurants determine the rate of wear of the block during use. The presence of the water soluble structurant retards the dissolution of the block when the block is exposed to water during use, thus retarding the rate of wear.

The skin cleansing bars also contain optional fillers selected from the group consisting of talc, clay, fumed silica, silica, silicates, carbonates, urea, cellulose fibers, sucrose, and inorganic salts such as sodium chloride , preferably hydrate electrolytes such as tetrasodium pyrophosphate and mixtures thereof. It is especially preferred to add the above fillers to bar compositions containing fatty acid soap as the main anionic surfactant.

Another optional ingredient is an oil/emollient which can be added to the cake composition as a benefit agent.

The various oil categories are set forth below.

Vegetable oils: peanut oil, castor oil, cocoa butter, coconut oil, corn oil, cottonseed oil, olive oil, palm kernel oil, canola oil, safflower oil, sesame seed oil, and soybean oil;

Esters: Butyl myristate, Cetyl palmitate, Decyl oleate, Glyceryl laurate, Glyceryl ricinoleate, Glyceryl stearate, Glyceryl isostearate, Hexyl laurate, Isobutyl Palmitate, Isocetyl Stearate, Isopropyl Isostearate, Isopropyl Laurate, Isopropyl Linoleate, Isopropyl Myristate, Isopropyl Palmitate, Stearin Propylene Glycol Monolaurate, Propylene Glycol Monolaurate, Propylene Glycol Ricinoleate, Propylene Glycol Stearate, and Propylene Glycol Isostearate.

Animal fats: Acytylated lanolin alcohol, lanolin, lard, mink oil and tallow;

Fatty acids and alcohols: behenic acid, palmitic acid, stearic acid, behenyl alcohol, cetyl alcohol, eicosanyl alcohol and isocetyl alcohol.

Examples of other oils/emollients include mineral oil, petrolatum, silicone oils such as dimethicone, lauryl lactate and myristyl lactate.

Alcohols include oleyl alcohol and isostearyl alcohol. Examples of ether derivatives include the carboxylic acid isostearyl ether carboxylic acid or oleyl ether carboxylic acid, or isostearyl ether alcohol or oleyl ether alcohol.

Liquid fatty acids that can be used are oleic acid, isostearic acid, linoleic acid, linolenic acid, ricinoleic acid, elaidic acid, arichidonic acid, myristoleic acid and palmitoleic acid. Ester derivatives include propylene glycol isostearate, propylene glycol oleate, glyceryl isostearate, glyceryl oleate and polyglyceryl diisostearate.

Another ingredient that may be included are exfoliating agents (ex-fbliants), such as polyethylene oxide beads, walnut shells, and almond kernels.

Liquid, hygroscopic zwitterionic and amphoteric surfactants may optionally be added to the extruded mass at low levels for the purpose of enhancing lather and skin mildness. These amphoteric and zwitterionic surfactants tend to be more hygroscopic than the specific solid amphoteric surfactants used in the subject invention, as shown in Table 1.

These surfactants are exemplified by derivatives that are broadly described as aliphatic quaternary ammonium, quaternary phosphonium, and quaternary sulfonium compounds, wherein the aliphatic radicals may be linear or branched, and wherein the aliphatic substituent One contains from about 8 to about 18 carbon atoms and one contains an anionic group such as carboxyl, sulfonate, sulfate, phosphate or phosphonate. The general formula of these compounds is: wherein ^R contains an alkyl, alkenyl, or hydroxyalkyl group of about 8 to about 18 carbon atoms, 0 to about 10 oxirane moieties, and 0 to about 1 glyceryl moiety; Y is selected from nitrogen , phosphorus and sulfur atoms; ^R3 is an alkyl or monohydroxyalkyl group containing about 1 to about 3 carbon atoms; when Y is a sulfur atom, X is 1, and when Y is a nitrogen or phosphorus atom, X is 2 ^R4 is an alkylene or hydroxyalkylene group having about 1 to about 4 carbon atoms, and Z is a group selected from carboxylate, sulfonate, sulfate, phosphonate and phosphate.

Examples of such surfactants include:

4-[N,N-bis(2-hydroxyethyl)-N-octadecylammonium]-butane-1-carboxylate,

5-[S-3-Hydroxypropyl-S-hexadecylsulfonium]-3-hydroxypentane-1-sulfate,

3-[P,P-diethyl-P-3,6,9-trioxatetradecyloxy (tetradexocyl)phosphonium]-2-hydroxypropane-1-phosphate,

3-[N,N-Dipropyl-N-3-dodecyloxy-2-hydroxypropylammonium]-propane-1-phosphonate,

3-(N,N-Dimethyl-N-hexadecylammonium)propane-1-sulfonate,

3-(N,N-Dimethyl-N-hexadecylammonium)-2-hydroxypropane-1-sulfonate,

4-[N,N-bis(2-hydroxyethyl)-N-(2-hydroxydodecyl)ammonium]-butane-1-carboxylate,

3-[S-Ethyl-S-(3-dodecyloxy-2-hydroxypropyl)sulfonium]-propane-1-phosphate,

3-[P,P-Dimethyl-P-dodecylphosphonium]-propane-1-phosphonate, and

5-[N,N-Bis(3-hydroxypropyl)-N-hexadecylammonium]-2-hydroxy-pentane-1-sulfate.

其中，R¹是7至18个碳原子的烷基或链烯基；R²和R³各自独立是1至3个碳原子的烷基、羟烷基或羧烷基；Amphoteric surfactants that may be used in this invention generally include at least one acid group. This may be a carboxyl or sulfonic acid group. They include quaternary nitrogen and are therefore quaternary amino acids. They should generally comprise alkyl or alkenyl groups of 7 to 18 carbon atoms. They are usually based on the general formula:

Wherein, R ¹ is an alkyl or alkenyl group of 7 to 18 carbon atoms; R ² and R ³ are each independently an alkyl, hydroxyalkyl or carboxyalkyl group of 1 to 3 carbon atoms;

n is 2 to 4;

m is 0 to 1;

X is an alkylene group of 1 to 3 carbon atoms optionally substituted with hydroxyl; and

Y is -CO ₂ - or -SO ₃ -.

和下式的氨基甜菜碱：这里m是2或3。Suitable amphoteric detergents in the above general formula include simple betaines of the formula:

and aminobetaines of the formula: Here m is 2 or 3.

R ¹ , R ² and R ³ in both formulas are as defined above. R ¹ may in particular be a mixture of C ₁₂ and C ₁₄ alkyl groups derived from coconut oil, such that at least half, preferably at least three quarters, of the R ¹ groups have 10 to 14 carbon atoms. Preferably ^R2 and ^R3 are methyl.

式中m是2或3，或这些的变体，其中-(CH₂)₃SO₃ ^-由下式取代：

在这些式中的R¹、R²和R³与先前讨论的一样。所述两性洗涤剂还可为下式的磺基甜菜碱：

或

式中m是2或3，或这些的变体，其中-(CH₂)₃SO₃ ^-由下式取代： The amphoteric detergent can also be a sultaine of the following formula: or

wherein m is 2 or 3, or a variant of these wherein -(CH ₂ ) ₃ SO ₃ ^- is replaced by:

R ¹ , R ² and R ³ in these formulas are as previously discussed. The amphoteric detergent can also be a sultaine of the following formula:

or

wherein m is 2 or 3, or a variant of these wherein -(CH ₂ ) ₃ SO ₃ ^- is replaced by:

R ¹ , R ² and R ³ in these formulas are as previously discussed.

Zwitterionic and/or amphoteric compounds that may be used may also include amphoacetates and diamphoacetates.

Optional amphoteric/zwitterionic compounds generally constitute 0 to 5% by weight of the cake composition, preferably 0.1 to 4%, more preferably 0.1 to 3% by weight.

In addition to one or more anionic, amphoteric and/or zwitterionic surfactants, the surfactant system may optionally comprise nonionic surfactants. Preferred nonionic surfactants are selected from alkyl amine oxides, most preferably C ₁₀ to C ₂₂ amine oxides.

Another optional component that may be added is a deflocculating polymer such as taught in US Pat. No. 5,147,576 to Montague, incorporated herein by reference.

In addition, the compositions of the present invention may include the following optional components:

Organic solvents, such as ethanol; auxiliary thickeners, such as carboxymethylcellulose, magnesium aluminum silicate, hydroxyethylcellulose, methylcellulose, carbopols, glucamide or ^Antil® from Rhone Poulenc; fragrances; chelates Mixing agents such as tetrasodium ethylenediaminetetraacetic acid (EDTA), EHDP or mixtures at 0.01 to 1%, preferably 0.01 to 0.05%; colorants, opacifiers and pearlizing agents such as zinc stearate, magnesium stearate, TiO _2. EGMS (ethylene glycol monostearate) or Lytron 621 (styrene/acrylate copolymer); all of these are useful to improve the appearance of the product or to enhance its cosmetic properties.

The composition may also contain antibacterial agents such as 2-hydroxy-4,2',4' trichlorodiphenyl ether (DP300); preservatives such as dimethyloldimethylhydantoin (Glydant XL1000) , parabens, sorbic acid, etc.

The composition may also contain cocoyl mono- or diethanolamide as suds suppressor, preferably also strongly ionizing salts such as sodium chloride and sodium sulfate.

For example, if appropriate, antioxidants such as butylated hydroxytoluene (BHT) may be used at optimum levels of about 0.01% or greater.

Cationic conditioners that can be used include Quatrisoft LM-200 Polyquaternium-24, Merquat Plus 3330-Polyquaternium-39 and Jaguar ^(R) type conditioners.

Polyethylene glycols that can be used include:

Polyox WSR-205 PEG14M,

Polyox WSR-N-60K PEG45M, or

Polyox WSR-N-750 PEG7M.

Thickeners that can be used include Amerchol Polymer HM 1500 (Nonoxynyl hydroxyethyl cellulose), Glucam DOE 120 (PEG 120 methyl glucose dioleate), Rewoderm ^(R) from Rewo Chemicals (PEG-modified glyceryl Cocoate, palmitate or tallowate), ^Antil® 141 (ex Goldschmidt).

The following examples are used to further illustrate the present invention, but not to limit the present invention.

Except where expressly stated in the working examples and comparative examples or elsewhere, all numbers expressed in the description, the amounts or ratios of materials or reaction conditions, the physical properties of materials and/or uses, can be expressed in accordance with the surrounding The modifications made by words are understood.

When used in this application, the term "comprising" should also be understood as indicating the presence of specified features, integers, steps, components, but not excluding the presence or addition of one or more of them, integers, steps, components or group.

All percentages are by weight unless otherwise stated. Process Skin Mildness Evaluation Protocol Four-Day Skin Contact Test Protocol: Using a skin contact test to evaluate anionic active agents with 1% (such as sodium cocoyl isethionate or Na-LED3A) and varying levels of structurants/co-activators The skin mildness of the aqueous dispersion. A patch (Hilltop ^(R) Chambers, size 25mm) was applied to the outer upper arm of the panelist with strap-on makeup (Scanpor ^(R) style). After each designated exposure period (24 hours for the first patch application and 18 hours for the second, third, and fourth day applications), the patches were removed and tested under consistent lighting by trained The site was rated visually by severity (erythema and dryness) by the examiner. Measurement of Foam Volume: The properties of the foam are investigated by means of graduated cylinder oscillation tests. Place 40 g of the test solution in a 250 ml PYREX ^™ covered cylinder. Foam was generated by shaking the graduated cylinder for 0.5 minutes. After the foam had sunk for 2.5 minutes, the height of the foam was measured. Measurement of Block Hardness: The hardness of the block was measured with a cone penetrometer. The penetration depth (in mm) is measured 2 minutes after releasing the penetrometer. Formulation Processing Technology

The extrusion process was routed for the blocks of the subject invention to produce high yield, high quality blocks and is widely used in the block manufacturing industry. The process is disclosed in detail in numerous patents and books. For example, Merilyn S. Mohr reviewed soap processing in his book "Soapmaking Techniques" in 1989, and Luis Spitz reviewed fatty acid soap bars and Processing of synthetic surfactant blocks. Both documents are hereby incorporated by reference into the title application. The drying and final parts of the extrusion process are briefly described here.

a) mixing and drying

Blocks were prepared using a mixer with S-blades. The components are mixed together at about 70-130°C, preferably 85-120°C, and the water content is adjusted to about 8-30% by weight. Cover the ingredients to prevent moisture loss and mix until uniform. The mixture is then dried (eg, by vacuum drying, spray drying, or air drying). The moisture content of samples extracted at different times during the drying phase was determined by Karl-Fischer titration with a turbo titrator.

b) Quench roll coating and mixing

At the final moisture level (approximately between 2% and 20%), the formulation is cast onto the drum of a hot film applicator, then quenched or milled, and chopped into chips or flakes.

c) Refining and layering

Using a series of homogenizers and plodders under vacuum, the chips or flakes are plodded, extruded into noodles and then into logs. The plodder head is heated to 45-50°C.

d) Stamping

The cut short pieces are punched into blocks using a die machine with a fixed shape die in place.

Blocks containing the solid amphoteric surfactant offer the same processing, skin mildness, and block performance advantages for those modified extrusion methods involving at least two or all of the following stages:

1) mixing and drying;

2) Refining and layering;

3) Stamping

For example, one of the extrusion methods, the "frozen block" method taught by US Patent Nos. 5,425,892, 5,225,098, 5,194,172, involves mixing-drying, layering and stamping. Thus, the "freeze block" method is suitable, and in fact the preferred processing route, for block compositions of the subject invention.

Another preferred modified extrusion method is carried out by coextrusion. In this method, the solid amphoteric surfactant (such as Deriphat 160) in the form of powder, pellets, flakes or granules is dry mixed with the base formulation which is also in solid form (i.e. powder, pellets, flakes or granules) . The mixture of said solids is quench rolled or ground into chips or flakes, which are then refined into new pellets, laminated into logs, and punched into blocks. Alternatively, the solid amphoteric surfactant can be directly added to a homogenizer or plodder through a solid feeding device, co-pressed with the basic block agent into a log shape, and punched into a block.

The block composition (A) provides sufficient block hardness without elastic properties. For example, pressing a 2 cm thick block of material to a 1 cm thickness with your fingers requires extraordinary force. If reached, the block will fracture, irreversibly damaging the block structure, irreversible back to 2cm thickness after release of force.

EXAMPLES Example 1 Benefits of using solid amphoteric surfactants on the block processing and block hardness

10 parts by weight of solid amphoteric surfactant (i.e. Deriphat 160 from Henkel Corp.) powder was mixed with 90 parts by weight of solid flakes of ^Dove® commercial block material in an S-blade mixer at a temperature of 40°C to 70°C Blended, the mixture was milled, refined into pellets and extruded into a log. The wood is then continuously stamped into blocks.

As a comparison, 10 parts by weight of a liquid, hygroscopic cocamidopropyl betaine was mixed with 90 parts by weight of ^Dove® commercial block material from the same batch number in a mixer at a temperature between 85°C and 120°C. The mixture with the target moisture content (approximately 5% of the total block composition) was cast into chill rolls and turned into flakes which were subsequently refined, extruded and punched into blocks. During this process, stickiness of the formulation was noted and the extrusion yield was significantly reduced. Adhesion of the formulation to the stamping die was also noted. The mixing and drying time period was also extended due to the cocamidopropyl betaine solution (40% active) and the high hygroscopicity of the cocamidopropyl betaine brought in additional water.

The hardness of the blocks containing 10% Deriphat 160 was determined and compared to the hardness of the blocks containing 10% cocamidopropyl betaine. The results in Figure 1 show that the blocks containing Deriphat 160 were harder than those containing Cocamidopropyl Betaine. Finally, when the 2 cm is pressed to a thickness of 1 cm with the thumb and forefinger (extraordinary force is required), the block breaks and returns to less than the original thickness of 2 cm (without exceeding 1 mm) within 5 seconds. Embodiment 2 as the solid amphoteric surfactant of foam booster

3 parts by weight of solid amphoteric surfactant (Deriphat 160) was added to 97 parts by weight of commercial Dove ^(R) block material, which was continuously processed into blocks using the standard extrusion process described in the process section. The lather volume of this bar was compared to a Dove based bar containing 3% cocamidopropyl betaine. The results are shown in Figure 2, both bars had similar lather and similar observable creaminess, indicating that the solid amphoteric surfactant provided similar lather enhancement as CAP betaine.

In a separate experiment, a foam of DEFI (a mixture of about 73% sodium cocoyl isethionate, 23% fatty acid, 3% sodium isethionate and 1% water) was tested with a mixture of DEFI/Deriphat160 Compare. The data in Figure 2 show that the solid amphoteric surfactant significantly promotes the foaming of DEFI and enhances the observed foam creamer. The weight ratio of the anionic surfactant to the solid amphoteric surfactant in Example 3 and the benefit of block foaming performance

As shown in Figure 3, the foam volume was measured at different DEFI/Deriphat 160 weight ratios, and the foam cream was observed. The results show that by adding Deriphat 160 to DEFI, the foam volume is increased. However, below the DEFI/Deriphat 160 weight ratio of 1:1.5, the foam became coarse and unstable. Therefore, the weight ratio of the anionic surfactant to the solid amphoteric surfactant is set at equal to and higher than 1:1.5, preferably 1:1, most preferably 2:1 to ensure increased creaminess and volume of the foam . Example 4 Excellent skin mildness of solid amphoteric surfactants for bars

The ability of the solid amphoteric surfactants to reduce skin irritation caused by anionic surfactants was investigated by conducting a skin contact test on human skin for 4 days. In this study, DEFI/Deriphat 160 blends were compared with different types of DEFI/liquid, hygroscopic amphoteric surfactant blends and DEFI alone.

The results showed that the solid amphoteric surfactant (Deriphat 160) was reduced by DEFI when compared to those liquid, hygroscopic amphoteric surfactants such as cocamidopropyl betaine and disodium cocoamphodiacetate. More effective in causing skin irritation. EXAMPLE 5 Excellent skin mildness of solid amphoteric surfactants for bars

As shown in Figure 5, the 4-day skin contact test on human skin showed that different weight ratios of DEFI/Deriphat were milder to human skin than those DEFI/cocamidopropyl betaine mixtures of the same weight ratio.

Claims (22)

1. A skin cleansing block composition comprising (a) 15 to 97% of a lathering anionic surfactant selected from synthetic anionic surfactants, fatty acid soaps and mixtures thereof; (b) 3 to 25% of special amphoteric surfactants that are in solid form at temperatures ranging from 18°C to 60°C; Wherein the weight ratio of the anionic surfactant (a) to the amphoteric surfactant (b) is equal to or greater than 1:1.5; wherein when the amphoteric surfactant contains less than 5% water, it is a crystalline solid having a melting temperature (T _m ) above 18°C, or an amorphous solid having a glass transition temperature (T _g ) above 18°C ;and wherein when said solid amphoteric surfactant contains less than 5% water, it is capable of absorbing 35% or less of its own weight in water at a relative humidity of 80% and a temperature of 26°C; and (c) 0-70% organic and inorganic structurants and fillers; (d) 0-30% emollients and humectants; (e) 0-5% conventional, hygroscopic amphoteric surfactants; (f) 0-20% nonionic surfactant; wherein said block composition provides a hard, inelastic extruded block; wherein said inelasticity is defined as when a 2 cm thick portion of said block is pressed to a 1 cm thickness with the thumb and forefinger, upon release of the pressure, The block portion will recover less than 2 cm of its original thickness within 5 seconds, with a range of 1 mm. 2. A composition according to claim 1 wherein said anionic surfactant is selected from the group consisting of sodium acyl isethionates, alkyl carboxylates and mixtures thereof. 3. A composition according to claims 1 and 2, wherein the anionic surfactant is from 25% to 97% of the total cake composition. 4. A composition according to any one of claims 1 to 3, wherein the amphoteric surfactant (b) is 4% to 20%, preferably 5% to 15%, of the total cake composition. 5. A composition according to any one of claims 1 to 4, wherein the weight ratio of said anionic surfactant to said amphoteric surfactant (b) is equal to or greater than 1:1. 6. A composition according to any one of claims 1 to 5, wherein the weight ratio of said anionic surfactant to said amphoteric surfactant (b) is equal to or greater than 2:1. 7. A composition according to any one of claims 1 to 6, wherein the amphoteric surfactant (b) is a crystalline material having a melting temperature greater than 20°C, preferably greater than 25°C. 8. A composition according to any one of claims 1 to 7, wherein the amphoteric surfactant (b) is an amorphous material having a glass transition temperature greater than 20°C, preferably greater than 25°C. 9. A composition according to any one of claims 1 to 8, wherein the amphoteric surfactant (b) used contains less than 5% water, preferably less than 2% water. 10. The composition according to claim 9, wherein said amphoteric surfactant (b) is capable of absorbing 32% or less, preferably 30% or less, of its own weight at a relative humidity of 80% and a temperature of 26° C. Even more preferred is 28% water or less. 11. A composition according to any one of claims 1 to 10, wherein said amphoteric surfactant (b) is a dialkali metal N-alkyliminodialkanoic acid, wherein said N-alkyl functional group having 10 to 22 carbons; disodium N-alkyliminodialkanoates, wherein the N-alkyl functional group has 10 to 22 carbons; dialkali metal N-alkyliminodipropionates, wherein The N-alkyl functional group has 10 to 22 carbons; the dialkali metal N-alkyliminodialkanoate, wherein the N-alkyl functional group has 12 to 18 carbons; or N-lauryl Disodium Aminodipropionate. 12. A composition according to claim 11, wherein disodium N-alkyliminodipropionate is provided in a solid form selected from powder, pellets, flakes and granules. 13. A composition according to any one of claims 1 to 12, wherein the anionic surfactant used contains 50% or more synthetic anionic surfactant, and structurant and filler (c) account for the total mass 15% or more of the composition. 14. The composition according to claim 13, wherein structurants and fillers (c) comprise 25% or more of the total block composition. 15. A composition according to claim 13 or 14, wherein structurants and fillers (c) comprise 45% or more of the total block composition. 16. A composition according to any one of claims 1 to 15, wherein the fatty acid soap constitutes 50% or more of the total anionic surfactants, said structurant and filler (c) are selected from talc, clay, gas phase Silica, silica, silicates, carbonates, urea, cellulose fibers, sucrose and inorganic salts. 17. The composition according to claim 16, wherein said inorganic salt is an alkali metal chloride. 18. A composition according to claim 16 or 17, wherein the inorganic salt is selected from aqueous electrolytes comprising tetrasodium pyrophosphate. 19. A composition according to any one of claims 1 to 18, wherein the hygroscopic amphoteric surfactant (e) is from 0 to 4%, preferably from 0 to 3%, of the total cake composition. 20. A composition according to any one of claims 1 to 19, wherein the non-ionic surfactant (f) is from 0 to 10% of the total cake composition. 21. A composition according to any one of the preceding claims, prepared by an extrusion process. 22. A composition according to any one of the preceding claims, prepared by a coextrusion process.

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